CRD4299-1 Cirrus Logic, Inc., CRD4299-1 Datasheet - Page 6

• Manufacturer Part Number: CRD4299-1
• Description: AC 97 AMR Reference Design
• Manufacturer: Cirrus Logic, Inc.

2.4.6 Aux In
•
•
•
2.4.7 Video In
•
•
2.4.8 Modem Audio Connection
The modem audio connection can be made through
the internal 4-pin (0.1 inch center) right-angled
connector. This connector carries both a mono in-
put and a mono output.
•
•
•
•
6
- Pin 3 : Common return
- Pin 4 : Right Channel
Internal 4-pin (0.1 inch center) right-angled
connector
Wired as:
- Pin 1 : Left Channel
- Pin 2 : Analog Ground
- Pin 3 : Analog Ground
- Pin 4 : Right Channel
Maximum input level: 2 Vrms
Internal 4-pin (0.1 inch center) right-angled
connector
- Pin 1 : Left Channel
- Pin 2 : Analog Ground
- Pin 3 : Analog Ground
- Pin 4 : Right Channel
Maximum input level: 2 Vrms
Internal 4 pin header (0.1 inch center)
- Pin 1 : Mono Out (to modem)
- Pin 2 : Analog Ground
- Pin 3 : Analog Ground
- Pin 4 : Phone In (from modem)
Maximum input level: 1 Vrms
Maximum output level: 1 Vrms
Minimum load impedance: 10 k
3. SCHEMATIC DESCRIPTION
Figures 11 through 17 show the schematics for the
CRD4299-1 AMR card. This section will describe
particular pages of the schematic that need to be
discussed.
3.1 Figure
The block diagram is an interconnection overview
between schematic pages.
3.2 Figure
The +5 V power pin is decoupled through C1 and
supplies power for the SPDIF_OUT circuit. All
ground pins are tied to digital ground except for B2,
which is tied to analog ground.
The AC-link, which consists of ASDOUT, ARST#,
ASYNC, ASDIN, and ABITCLK, transfers digital
audio data between the audio codec and the host.
PC_BEEP_BUS routes the beep/speaker signal
from the motherboard to the audio subsystem, for
use in hearing POST codes (refer to the Intel Au-
dio/Modem Riser Specification [2]).
The PRIMARY_DN# signal indicates the presence
or the absence of a primary codec on the mother-
board. The MSTRCLK is the 24.576 MHz master
clock for the AC ‘97 link. Populate R51 when the
Codec is the primary codec. Populate R50 when the
Codec is the secondary codec.
The CS4297 does not support S/PDIF. Iin this case,
R3 should be populated so the S/PDIF signal orig-
inates from the AMR bus. For a CS4297A/99, by
populating R2 instead of R3, the S/PDIF signal
originates from the codec, bypassing the AMR bus.
3.3 Figure
The CS4299 requires both a digital +3.3 V and an
analog +5 V supply. The digital power is supplied
from the AMR bus. A separate regulator is recom-
mended for the analog voltage supply to provide
good audio signal quality. A Motorola MC78L05
regulates the +12 V supply from the AMR bus
11
12
13
: Block Diagram
: AMR Bus Interface
: Power Supply
CRD4299-1 AMR
DS319RD1A1